Updated: Oct 4, 2021
Since penguins lifestyles require them to be efficient both on land and in the water, their eyes have several adaptations that allow them to see perfectly in these two very different environments.
This really is quite special when you consider how different the medium of seawater is compared to air in terms of the physics of light movement, refraction and general irritation to the eye.
Firstly, penguins have an extra, transparent eyelid called a nictitating membrane that protects the eye by keeping debris and saltwater out. Watch carefully as @2oceansaquarium rescued rockhopper penguin, Jasmine, shows off her nictitating membrane in slow motion.
Furthermore, a penguins corneas are flattened by strong muscles surrounding their eyes. This prevents light from bending when it enters their eyes and blurring their vision underwater. With the ability to change the shape of their eye lens, they can see crisp, sharp and perfectly clearly both in and out of the water. Penguins, therefore, never have to wear goggles or a dive mask when they venture out into the ocean.